Brettanomyces Project

A Bit on Brettanomyces

Brettanomyces yeast species were traditionally known for their important role in the production of Lambic, sour and wild ales such as the Flemish Reds and Oud Bruins and one particular Trappist beer. Over the past decade, various Brettanomyces strains have seen increasing use in the craft brewing industry. In the early to mid-2000s, primary fermentation with Brettanomyces was infrequent and typically a one-off, occurring out of experimentation. Very little information previously existed regarding pure culture fermentative capabilities and the aromatic compounds produced by various strains of Brettanomyces. Brettanomyces yeast species have been the subjects of previous studies conducted over the past century, however the majority of the research was focused on enhancing the knowledge of the wine industry only.

Initial Discovery and Characterization

The earliest published account came from a paper presented in 1904 to the Institute of Brewing in which N. Hjelte Claussen described the discovery of a newly isolated yeast that he proposed be called Brettanomyces, Latin for British brewing fungus. Claussen went on to state it was responsible for the secondary fermentation and development of characteristic flavors and aromas of the finest English stock ales.

In 1940 M.T.J. Custers presented the first systematic investigation on Brettanomyces. At that time Custers believed Brettanomyces yeasts were only found in English and Belgian beer. We now know it is a yeast that is found around the world and in every known wine making region, not specifically a Belgian yeast, but more recognizable in English stock ales.

Brettanomyces ≠ Sour

Brettanomyces, familiarly known as Brett, is considered wild yeast and is responsible for the flavor and aroma of sour beer. It is not responsible for the acidity found in sour beer; in order for a beer to be sour it has to contain lactic acid producing bacteria Lactobacillus and Pediococcus. Therefore a beer may contain Brett and not be sour. We make a few Brettanomyces beers which do not contain any bacteria and therefore are not sour.

Brett = Wild

Wild is to Brettanomyces as Ale is to Saccharomyces cerevisiae, which is the top fermenting yeast known as traditional brewer’s yeast. Wild is the best designation you can use for these beers as there are many forms of wild beers, some being sour and others not. A barrel-aged Saison with Brettanomyces is wild, as is a 100% Brettanomyces beer, though neither are sour. However, a Flemish Red style of beer is a wild beer, just as a Sour Golden with fruit is wild. Think of wild as a broad third category of beer: ale, lager and wild.

Brettanomyces Aroma Profiles

Versatility and Role at Crooked Stave

From the table above, it is clear that not all characteristics of Brettanomyces are perceived as positive and complimentary to a beer. Some of this is because Brettanomyces historically had a reputation in the wine industry as being a spoilage organism, imparting less desirable traits to finished wine. At Crooked Stave we search out the complex, delicate characteristics that Brettanomyces can provide. We find that when great care is taken in the selection of strains, and when the right conditions are provided for the yeast to flourish, they lend anything from orange, lemon, or lime characteristics to stone fruit, apples, ripe mangoes, and pineapple.

Brett will also impart dry, earthy, leathery notes, and we feel that these flavors and aromas are complementary to balance the tart and vinous characteristics while also adding a layer of complexity not found in most beers. We go to great lengths to ensure our beers retain body, mouthfeel, and a round finish from the first pour to the last sip in your glass.